/* Name: Copyright: Deitel C How to Program Author: StackOverflow1453 Date: 5/20/2013 11:51:08 AM Description: (Knight’s Tour) One of the more interesting puzzlers for chess buffs is the Knight's Tour problem, originally proposed by the mathematician Euler. The question is this: Can the chess piece called the knight move around an empty chessboard and touch each of the 64 squares once and only once? We study this intriguing problem in depth here. The knight makes L-shaped moves (over two in one direction and then over one in a perpendicular direction). Thus, from a square in the middle of an empty chessboard, the knight can make eight different moves (numbered 0 through 7) as shown in Fig. 6.25. a) Draw an 8-by-8 chessboard on a sheet of paper and attempt a Knight's Tour by hand. Put a 1 in the first square you move to, a 2 in the second square, a 3 in the third, etc. Before starting the tour, estimate how far you think you will get, remembering that a full tour consists of 64 moves. How far did you get? Were you close to the estimate? b) Now let us develop a program that will move the knight around a chessboard. The board itself is represented by an 8- by-8 double-subscripted array board. Each of the squares is initialized to zero. We describe each of the eight possible moves in terms of both their horizontal and vertical components. For example, a move of type 0 as shown in Fig. 6.25 consists of moving two squares horizontally to the right and one square vertically upward. Move 2 consists of moving one square horizontally to the left and two squares vertically upward. Horizontal moves to the left and vertical moves upward are indicated with negative numbers. The eight moves may be described by two single-subscripted arrays, horizontal and vertical, as follows: horizontal[ 0 ] = 2 horizontal[ 1 ] = 1 horizontal[ 2 ] = -1 horizontal[ 3 ] = -2 horizontal[ 4 ] = -2 horizontal[ 5 ] = -1 horizontal[ 6 ] = 1 horizontal[ 7 ] = 2 vertical[ 0 ] = -1 vertical[ 1 ] = -2 vertical[ 2 ] = -2 vertical[ 3 ] = -1 vertical[ 4 ] = 1 vertical[ 5 ] = 2 vertical[ 6 ] = 2 vertical[ 7 ] = 1 Let the variables currentRow and currentColumn indicate the row and column of the knight's current position on the board. To make a move of type moveNumber, where moveNumber is between 0 and 7, your program uses the statements currentRow += vertical[ moveNumber ]; currentColumn += horizontal[ moveNumber ]; Keep a counter that varies from 1 to 64. Record the latest count in each square the knight moves to. Remember to test each potential move to see if the knight has already visited that square. And, of course, test every potential move to make sure that the knight does not land off the chessboard. Now write a program to move the knight around the chessboard. Run the program. How many moves did the knight make? */ #include <stdio.h> #include <stdlib.h> #include <time.h> int randomiseMovement(void); int printBoard(void); void clearChessBoard(void); void copyRecordArray(int b[][8]); void printRecordArray(int b[][8]); int validOrNot(int mn); void moveKnight(int moveno); void initialize(); int isThereEmptyLocationAround(); //these are declared here for each function to reach! //These two single subscript arrays will be used to move the knight as L shape according to array subscript int horizontal[8]; int vertical[8]; //declare currrent position int currentRow; int currentColumn; //Movement counter int count=0; int chessBoard[8][8]={0}; //the array which holds the biggest record int recordHolder[8][8]={0}; int flag=0; int moveNumber=0;// moveNumberB1=0, moveNumberB2=0, moveNumberB3=0; int m=1; int main(void){ int biggestCoverage=0; //initialize horizontal move of knight horizontal[ 0 ] = 2; horizontal[ 1 ] = 1; horizontal[ 2 ] = -1; horizontal[ 3 ] = -2; horizontal[ 4 ] = -2; horizontal[ 5 ] = -1; horizontal[ 6 ] = 1; horizontal[ 7 ] = 2; //intialize vertical move of the knight vertical[ 0 ] = -1; vertical[ 1 ] = -2; vertical[ 2 ] = -2; vertical[ 3 ] = -1; vertical[ 4 ] = 1; vertical[ 5 ] = 2; vertical[ 6 ] = 2; vertical[ 7 ] = 1; srand(time(NULL)); printf("____________________________________________________________________________\n"); while (biggestCoverage<60){ initialize(); moveNumber=randomiseMovement(); printf("Move randomised to: %d\n", moveNumber); printf("____________________________________________________________________________\n"); printf("STARTING POS IS: [%d][%d]\n", currentRow, currentColumn); do { //First check if moveNumber position is available //Then move the knight accordingly if(validOrNot(moveNumber)) moveKnight(moveNumber); else if (isThereEmptyLocationAround()) { moveNumber=randomiseMovement(); } else { flag=-1; } } while (flag!=-1); m=printBoard(); if(m>biggestCoverage){ biggestCoverage=m; copyRecordArray(chessBoard); } printf("\n\nGINES REKORU: %d\n", biggestCoverage); printRecordArray(recordHolder); } printf("\n"); getch(); return 0; } int randomiseMovement(void){ return rand()%8; } void copyRecordArray(int b[][8]){ int i,j; for (i = 0; i < 8; i++) { for (j = 0; j < 8; j++) { recordHolder[i][j]=b[i][j]; } } } int validOrNot(int mn){ return ( chessBoard[currentRow+vertical[mn]][currentColumn+horizontal[mn]]==0 && ( currentRow+vertical[mn] )>=0 && ( currentRow+vertical[mn] )<8 && ( currentColumn+horizontal[mn] ) >=0 && ( currentColumn+horizontal[mn] ) <8 ); } void moveKnight(int moveno){ currentRow+=vertical[moveno]; currentColumn+=horizontal[moveno]; printf("Knight has moved to chessBoard[%d][%d].\n",currentRow,currentColumn); count++; printf("Move count is %d.\n",count); chessBoard[currentRow][currentColumn]=count; } int isThereEmptyLocationAround(){ int i; for (i = 0; i < 8; i++) { if(validOrNot(i)) return 1; } return 0; } int printBoard(void){ int i,j,onesCount=0; printf("\n"); for (i = 0; i < 8; i++) { printf("\n"); for (j = 0; j < 8; j++) { printf("%2d ", chessBoard[i][j]); if(chessBoard[i][j]>0) onesCount++; } } return onesCount; } void printRecordArray(int b[][8]){ int i,j; printf("\n BIGGEST RECORDED ARRAY IS: \n"); printf("\n"); for (i = 0; i < 8; i++) { printf("\n"); for (j = 0; j < 8; j++) { printf("%2d ", b[i][j]); } } printf("\n"); } void clearChessBoard(void){ int i,j; for (i = 0; i < 8; i++) { for (j = 0; j < 8; j++) { chessBoard[i][j]=0; } } } void initialize(){ flag=0; clearChessBoard(); currentColumn=rand()%8; currentRow=rand()%8; chessBoard[currentRow][currentColumn]=1; count=1,m=0; }

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